Nice demo, I like it 
I’d just like to add that you can use (collection) factories to draw large maps (in Kanji Adventure , the exploration map is 100x100 tiles large), you just have to create a routine that manages creation and deletion of tiles that are on-/offscreen respectively.
Oh, and one (pretty significant) performance optimization that I found out a couple days back - make sure to cut up the data that you are going to use into multiple lua tables. Accessing the following tables:
self.tile_styles = self.tilemap()["layers"][1]["data"]
self.object_styles = self.tilemap()["layers"][3]["data"]
self.large_object_styles = self.tilemap()["layers"][4]["data"]
self.grayscale_mods = self.tilemap()["layers"][5]["data"]
self.tilesets = self.tilemap()["tilesets"]
is much faster than accessing them via
local res = sys.load_resource("/maps/" .. self.map_name .. ".lua")
self.tilemap = assert(loadstring(res))
There is also a helpful list of tips on performance in Lua over at https://www.lua.org/gems/sample.pdf